Abstract: Upon release, gametes from individual corals of the same species must locate each other, complete fertilization, survive during development in the water column, locate the reef, settle and undergo metamorphosis. Failure at any of these stages impacts population dynamics and can threaten the persistence of a given species. However, the molecular bases for these critical processes remain largely unknown. For example, during fertilization, gametes from individuals of the same species must locate each other, but what are the receptors on coral eggs and sperm that are responsible for gamete recognition and species-restricted fertilization? As larvae develop, how do they detect the cues (light and chemicals) in their environment that are known to influence larval navigation and settlement? Here, I present progress from two of my current projects: 1) identification and characterization of photo- and chemoreceptors involved in larval navigation and settlement; 2) identification of egg receptors responsible for species-restricted fertilization. Acropora spp. posses hundreds of transmembrane receptors. Of these, I have identified six putative opsins (receptors responsible for visual and non-visual photoreception in animals) and at least 10 putative olfactory receptors. Developmental expression profiles indicate that expression peaks during early developmental stages, suggesting that these genes may play roles in larval navigation and/or settlement. I am currently working to localize the messenger RNAs and proteins in coral planulae and demonstrate activity of these receptors in response to light or chemical cues. In vertebrates, zona pellucida (ZP) domain-containing proteins are essential for sperm binding and species-restricted fertilization. Using a candidate gene approach I have identified four ZP genes expressed in unfertilized A. millepora eggs. I have gel-purified proteins from A. millepora eggs and am currently sequencing these to confirm the presence of ZP proteins and identify other potential candidates. I am also raising coral ZP antibodies for use in fertilization assays, to block fertilization and demonstrate involvement of the ZPs in coral fertilization.

Biography: Ben Mason earned his PhD in Marine Biology in 2011 from the University of Miami. His research has revolved around coral reproduction and larval biology/ecology, including investigations of the effects of ocean acidification on the early life history stages of corals and the mechanisms of light detection and influence of light on larval settlement. Ben joined the ARC Centre of Excellence for Coral Reef Studies in 2012 as a National Science Foundation International Postdoctoral Fellow. His current research includes investigations of the molecular mechanisms underpinning photo- and chemoreception in coral larvae as well as gamete recognition and species-restricted fertilization in corals.